JP2017515059A - Bulk metallic glass-based wave gear device and system and method for implementing wave gear device components - Google Patents

Abstract

The system and method according to embodiments of the present invention embody bulk metallic glass-based wave gear devices and wave gear device components. In one embodiment, the wave gear device has a wave generator, a flex spline that itself has a first gear tooth set (flex spline), and a second gear tooth set itself. A circular spline and at least one of the wave generator, flexspline, and circular spline includes a bulk metallic glass-based material. [Selection] Figure 1

Description

Description of Federally Funded Research and Development The present invention disclosed herein is made in the working work contracted with NASA and is maintained by the US Public Code 96-517 (35 U.S.C. §202 ).

  The present invention relates generally to bulk metallic glass-based strain wave gears and wave gear device components.

  The wave gear system, also known as Harmonic Drive®, is a unique gear system with a high reduction ratio, high torque-weight ratio and torque-volume ratio, nearly zero backlash (component potential ) And many other benefits can be provided. Typically, a wave gear device has an elliptical wave generator that is mounted within a flexspline, where the flexspline matches the elliptical waveform produced by the wave generator (wave generator). Has a set of ball bearings so that the flexspline rotates about an elliptical central axis relative to the wave generator. The flexspline is usually placed in a ring-shaped circular spline, and the flexspline has a set of gear teeth set along its outer periphery that is elliptical, and this gear tooth set is It meshes with the gear teeth arranged along the inner circumference of the rim-shaped circular spline (circular spline). Usually, a flexspline has fewer teeth than a circular spline. In particular, the flexspline is formed from a flexible material, and when the gear teeth of the flexspline and the circular spline are engaged, the wave generator can rotate in a first direction relative to the circular spline, thereby in the opposite second direction. Causes flexspline deformation and associated rotation. Normally, input torque is supplied to the wave generator and the flexspline results in output torque. In general, the rotational speed of the wave generator is considerably faster than the rotational speed of the flexspline. Therefore, the wave gear device can achieve a high reduction ratio with respect to the gear system and can be realized with a smaller form factor.

  It is also noted that in some alternative configurations, a circular spline can be used to hold the flexspline fixed and produce output torque.

  As can be inferred, the operation of the wave gearing has a special meaning and depends on a gear system that is designed very precisely. For example, the geometry (geometric surface shape) of the components in a wave gear device must be made with extreme accuracy to produce the desired motion. In addition, the components of the wave gear device must be made from materials that can achieve the desired function. In particular, the flexspline must be flexible enough to withstand high frequency cyclic deformations and at the same time sufficient to accommodate the loads that the wave gearing is expected to be exposed to. Must have sufficient strength.

  Because of these constraints, traditional wave gearing has been made large from steel, because it has been demonstrated that steel has the necessary material properties, and steel is machined to the desired geometry. Because it can be done. However, machining steel as a component can be quite expensive. For example, in many instances, steel-based wave gear devices can cost in the order of $ 1000 to $ 2000 due to expensive manufacturing processes.

  In some cases, the harmonic drive is made from a thermoplastic material. Thermoplastic materials (e.g. polymers) can be cast into the shape of the component (e.g. by an injection molding process), thereby increasing the cost typically practiced in the manufacture of steel-based wave gear devices. Machining processes can be avoided. However, wave gear devices made from thermoplastic materials are not as strong as wave gear devices made from steel.

  The systems and methods according to embodiments of the present invention embody bulk metallic glass-based wave gear devices and wave gear device components. In one embodiment, the wave gear device comprises a wave generator, a flexspline having a first gear tooth set, and a circular spline having a second gear tooth set (circular And at least one of the wave generator, flexspline, and circular spline includes a bulk metallic glass-based material.

  In other embodiments, the wave generator has a wave generator plug and a bearing.

  In yet another embodiment, the bearing is a ball bearing.

  In other embodiments, each of the wave generator, flexspline, and circular spline comprises a bulk metallic glass-based material.

  In still other embodiments, at least one of the first set of gear teeth and the second set gear teeth includes a bulk metallic glass-based material.

  In still other embodiments, each of the first set of gear teeth and the second set of gear teeth includes a bulk metallic glass-based material.

  In yet another embodiment, the wave generator has a ball bearing that includes a bulk metallic glass-based material.

  In yet another embodiment, the element of the bulk metallic glass-based material that is present in the maximum amount is one of Fe, Zr, Ti, Ni, Hf, and Cu.

In yet another embodiment, the element of the bulk metallic glass-based material is Ni ₄₀ Zr _28.5 Ti _16.5 Al ₁₀ Cu ₅ . In yet another embodiment, the wave generator comprises a wave generator plug having an elliptical cross-sectional view, and a bearing having an inner race, an outer race, and a plurality of rolling members, the wave generator plug being a bearing. Arranged within the bearing to allow the bearing to conform to the elliptical shape of the wave generator plug, at least one of the wave generator plug and the bearing comprises a bulk metallic glass-based material.

  In other embodiments, the bearing is a ball bearing.

  In yet another embodiment, the flexspline comprises a flexible body that defines a circular shape, the circular perimeter defines a set of gear teeth, and the flexible body includes a bulk metallic glass-based material. .

  In still other embodiments, a set of gear teeth includes a bulk metallic glass-based material.

  In yet another embodiment, the circular spline comprises a ring-shaped body, the inner periphery of the ring-shaped body defines a set of gear teeth, and the ring-shaped body includes a bulk metallic glass-based material.

  In a further embodiment, a set of gear teeth includes a bulk metallic glass-based material.

  In yet another embodiment, a method of making a wave gear device component comprises forming a BMG-based material using a mold associated with one of a thermoplastic forming technique and a casting technique, and the BMG-based material Wave generator plug, inner race, outer race, rolling element, flexspline, flexspline without one set of gear teeth, circular spline, circular spline without one set of gear teeth, flexspline Are formed as one of a set of gear teeth to be incorporated into a circular spline and a set of gear teeth to be incorporated into a circular spline.

  In yet another embodiment, the method of making a wave gear device component further comprises machining the BMG-based material after molding by either thermoplastic forming technology or casting technology.

  In other embodiments, the BMG-based material is molded as one of a flexspline without a set of gear teeth and a circular spline without a set of gear teeth, and the gear teeth are relative to the BMG-based material. Machine.

  In yet another embodiment, the BMG-based material is molded as one of a flexspline without a set of gear teeth and a circular spline without a set of gear teeth, and the gear teeth are formed into a twin roll. Use technology to embody BMG-based materials.

  In yet other embodiments, the BMG-based material is molded using one of direct casting techniques, blow molding techniques, and centrifugal casting techniques.

4 shows a wave gear device that can be made from a BMG-based material according to an embodiment of the present invention. The operation | movement of the wave gear apparatus by embodiment of this invention is shown. The operation | movement of the wave gear apparatus by embodiment of this invention is shown. The operation | movement of the wave gear apparatus by embodiment of this invention is shown. The operation | movement of the wave gear apparatus by embodiment of this invention is shown. The normal life expectancy of a wave gear device is shown. FIG. 6 illustrates fatigue properties of BMG-based materials that can be embodied in a wave gear device component according to an embodiment of the present invention. FIG. 6 illustrates fatigue properties of BMG-based materials that can be embodied in a wave gear device component according to an embodiment of the present invention. FIG. 4 illustrates the wear resistance characteristics of a titanium-nium BMG-based material that can be embodied in a wave gear device component according to an embodiment of the present invention. 2 illustrates a method of forming a BMG-based wave gear device component according to an embodiment of the present invention. FIG. 6 illustrates gear formation using casting techniques in accordance with an embodiment of the present invention. FIG. FIG. 6 illustrates gear formation using casting techniques in accordance with an embodiment of the present invention. FIG. FIG. 6 illustrates gear formation using casting techniques in accordance with an embodiment of the present invention. FIG. FIG. 6 illustrates gear formation using casting techniques in accordance with an embodiment of the present invention. FIG. FIG. 4 illustrates the fabrication of a wave gear device component using casting techniques, according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using casting techniques, according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using casting techniques, according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using casting techniques, according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using a BMG-based material in sheet form in conjunction with a thermoplastic forming technique, according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using a BMG-based material in sheet form in conjunction with a thermoplastic forming technique, according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using a BMG-based material in sheet form in conjunction with a thermoplastic forming technique, according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using spin formation technology, in accordance with an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using spin formation technology, in accordance with an embodiment of the present invention. FIG. 6 illustrates the creation of a wave gear device component using spin formation technology, in accordance with an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using blow molding technology according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using blow molding technology according to an embodiment of the present invention. FIG. 4 illustrates the fabrication of a wave gear device component using blow molding technology according to an embodiment of the present invention. FIG. 6 illustrates the formation of a wave gear device component using centrifugal casting according to an embodiment of the present invention. FIG. 6 illustrates the formation of a wave gear device component using centrifugal casting according to an embodiment of the present invention. FIG. 6 illustrates the formation of a wave gear component by thermoplastically forming a BMG type material in powder form, in accordance with an embodiment of the present invention. FIG. 6 illustrates the formation of a wave gear component by thermoplastically forming a BMG type material in powder form, in accordance with an embodiment of the present invention. FIG. 6 illustrates the formation of a wave gear component by thermoplastically forming a BMG type material in powder form, in accordance with an embodiment of the present invention. FIG. 4 illustrates implementing gear teeth for a BMG based wave gear component using a twin roll forming technique according to an embodiment of the present invention. FIG. 15 illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15 illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15 illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15 illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15 illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15 illustrates the formation of a flexspline by the process outlined in FIG. 14 according to an embodiment of the present invention. In the production of wave gear device components according to embodiments of the present invention, it is shown that the casting process is well controlled. FIG. 5 illustrates that wave gear components according to embodiments of the present invention can be made at any suitable scale. Fig. 4 shows the creation of a circular spline according to an embodiment of the invention. Fig. 4 shows the creation of a circular spline according to an embodiment of the invention. 6 illustrates the cost benefit of casting or thermoplastic forming wave gear device components from BMG-based materials according to embodiments of the present invention. A steel flexspline is shown.

  Referring to the drawings, systems and methods for implementing bulk metallic glass-based wave gear devices and wave gear device components are shown. In many embodiments, at least one of the wave generator, flexspline, and circular spline in the corresponding wave gear device shall comprise a bulk metallic glass-based material. In many embodiments, at least the flexspline will comprise a bulk metallic glass-based material. In many embodiments, each of the wave generator, flexspline, and circular spline will comprise a bulk metallic glass-based material.

  Metallic glasses, also known as amorphous alloys (or alternatively amorphous metals), are characterized by an irregular atomic scale structure whatever their metal component elements, ie ordinary metal materials are common Although having a highly ordered structure, metallic glass materials are characterized by an irregular atomic structure. In particular, metallic glasses generally have many useful metallic properties that can be implemented as highly effective engineering materials. For example, metallic glasses are generally much harder than conventional metals and are generally tougher than ceramic materials. They are also relatively resistant to corrosion and can be highly conductive, unlike conventional glasses. Importantly, the production of the metallic glass material itself is suitable for relatively simple processing. In particular, the production of metallic glass can be adapted to an injection molding process or any similar casting process.

Nevertheless, the production of metallic glass presents challenges that limit its feasibility as an engineering material. In particular, metallic glasses generally heat a metal alloy above its melting point and rapidly cool the melt to solidify to avoid its crystallization, thereby forming a metallic glass. The early metallic glass required a drastic cooling rate on the order of, for example, 10 ⁶ K / s, and there was a limit to the thickness that could be formed. In fact, due to this thickness limitation, metallic glass was initially limited to coating applications. However, later, special alloy compositions that were more resistant to crystallization were developed, which allowed metal glasses to be formed with a much slower cooling rate and thus made considerably thicker (e.g. Thicker than 1 mm). These thicker metallic glasses are known as “bulk metallic glasses” (“BMGs”).

  In addition to the development of BMG, “bulk metallic glass-matrix composites” (BMGMCs) were also developed. BMGMCs have an amorphous structure of BMGs, but are characterized by including the crystalline phase of the material in the amorphous structure matrix. For example, the crystalline phase can exist in a dendritic form. The crystalline phase allows the material to have higher ductility compared to a material that is entirely composed of an amorphous structure.

  Even with these developments, current technology has not yet fully evaluated the beneficial material properties of BMG-based materials (throughout this specification, the term “BMG-based material” refers to BMGs and Meaning that it contains BMGMCs). As a result, the use of BMG-based materials has been limited to engineering applications. For example, various publications have concluded and extensively demonstrated that the viability of BMG-based materials is almost limited to microscale structures (see, for example, Non-Patent Document 1 (G. Kumar et al. , Adv. Mater. 2011, 23, 461-476), and Non-Patent Document 2 (M. Ashby et al., Scripta Materialia 54 (2006) 321-326), the disclosures of which are hereby incorporated by reference. To be incorporated). This is partly because the material properties of BMG materials, including fracture mechanics, correlate with sample size. For example, it has been observed that the ductility of BMG material is inversely correlated with its thickness (eg, Non-Patent Document 3 (Conner, Journal of Applied Physics, Volume 94, Number 2, July 15, 2003, pgs. 904-911). ), The disclosure of which is hereby incorporated by reference). Importantly, as component dimensions increase, they are more susceptible to brittle fracture. Thus, for these or other reasons, those skilled in the art generally advise that BMG-based materials can be excellent materials for microscale structures such as MEMS devices, but in general macroscale components (See, for example, Non-Patent Document 1 (G. Kumar et al., Adv. Mater. 2011, 23, 461-476)). In fact, G. Kumar et al. Summarized that brittle fracture is associated with plastic region size, and a sample thickness of about 10 times the plastic region radius can exhibit a bending plasticity of 5%. Therefore, G. Kumar et al. Concluded that a 1 mm thick sample of Vitreloy can exhibit 5% bend plasticity.

  Conventional understanding suggests that the use of BMG-based materials is limited, but also promotes the wear resistance of BMG-based materials (for example, Non-Patent Document 4 (Wu, Trans. Nonferrous Met Soc. China22 (2012), 585-589; Wu, Intermetallics 25 (2012) 115-125), Non-Patent Document 5 (Kong, Tribal Lett (2009) 35: 151-158; Zenebe, Tribol Lett (2012) 47 : 131-138), Non-Patent Document 6 (Chen, J. Mater. Res., Vol. 26, No. 20, Oct 28, 2011; Liu, Tribol Lett (2012) 46: 131-138). The disclosures of which are hereby incorporated by reference). For clarity, “wear” usually refers to the displacement of the material surface as a direct result of mechanical interaction with other materials. In general, it is understood that the resistance of a material to wear generally increases with its hardness, i.e., the harder the material, the less susceptible to wear (e.g., Non-Patent Document 7 (IL Singer, Wear, Volume 195, Issues 1-2, July 1996, Pages 7-20)). Based on these understandings, the expected wear resistance properties of BMGs indicate that gears have a wide range of mechanical interactions and are therefore subject to wear, making them an excellent candidate for materials for making small gears. (For example, Non-Patent Document 8 (Chen, J. Mater. Res., Vol. 26, No. 20, Oct 28, 2011), Non-Patent Document 9 (Huang, Intermetallics 19 ( 2011) 1385-1389), Non-Patent Document 10 (Liu, Tribol Lett (2009) 33: 205-210), Non-Patent Document 11 (Zhang, Materials Science and Engineering A, 475 (2008) 124-127), Non-Patent Reference 12 (Ishida, Materials Science and Engineering A, 449-451 (2007) 149-154), the disclosures of which are incorporated herein by reference). Thus, in accordance with the above insights, microscale gears have been made (see Non-Patent Document 12, the disclosure of which is hereby incorporated by reference).

  However, contrary to the conventional insights described above, Hofmann et al. Demonstrated that BMG-based materials can be beneficially embodied in a variety of other applications. For example, US Pat. No. 6,928,109 to Hofmann et al. Discloses how BMG-based materials can be developed for making gears on a macro scale. In particular, Patent Document 1 demonstrated that Mr. Ishida demonstrated the production of BMG gears, but the demonstration was that the gears produced were of small dimensions (and thus the destruction of the same mode as a macro-sized engineering part). He explained that the gear was limited insofar as it operated using a lubricant that could reduce the tendency to brittle fracture. In general, Hofmann et al. Explain that the prior art is mainly related to making use of the wear resistance properties of BMG-based materials and, as a result, focusing on achieving the hardest BMG-based materials. This design approach is limited as long as the hardest material is susceptible to other failure modes. In fact, Hofmann et al. Have demonstrated that the hardest BMG-based materials in making macro-scale gears generally yield gears that break during operation. Thus, Hofmann et al. Disclose that BMG-based materials can be developed to have advantageous properties with respect to fracture toughness and thereby create macro-scale gears that do not necessarily require a lubricant to function. ing. U.S. Pat. No. 6,057,097 is incorporated herein by reference. In addition, US Pat. No. 6,943,932 (Hofmann et al., US Pat. No. 13,942,932) describes that BMG-based materials have other advantageous material properties and are therefore used to create macro-scale compliance mechanisms. We disclose what we can do. The disclosure of Patent Document 2 is incorporated herein by reference.

  Contrary to this background, it is clear that the versatility of BMG-based materials has not been fully evaluated. This specification discloses how BMG-based materials can be developed and thereby incorporated into wave gearing and wave gearing components. For example, BMG-based materials can be developed to have high fatigue durability, high fracture toughness, excellent sliding friction properties, low density, and high elasticity. Thus, when developed to have these properties, BMG-based materials are preferably embodied in the manufacture of the component components of a wave gear device, thereby embodying many aspects of the operation of the wave gear device. Can do. For example, a wave gear device incorporating a BMG-based material can withstand a larger operating load, can be lighter, and can have a longer useful life. Further, since the BMG-based material can be cast or thermoplastically formed to have a desired geometry (geometric surface shape), it can be cast or thermoplastically formed into the shape of a component of a wave gear device. can do. In this way, expensive machining processes that are ubiquitous in the manufacture of steel-based wave gearing and wave gearing components can be reduced if not eliminated. In short, wave gear devices and wave gear device components incorporating BMG-based materials can provide significantly improved performance at a lower cost. The general operation of the wave gear device will be described in detail below.

Wave Gear Device Operation In many embodiments of the present invention, wave gear devices and wave gear device components are provided incorporating BMG-based materials, thereby having improved performance characteristics. In order to explain the background, the basic operation principle of the wave gear device will be outlined.

  FIG. 1 shows an exploded view of a representative wave gear device that can be made from a BMG-based material according to an embodiment of the present invention. In particular, the wave gear device 100 includes a wave generating device (wave generator) 102, a flex spline (flex spline) 108, and a circular spline (circular spline) 112. The illustrated wave generator 102 includes a wave generator plug 104 and a ball bearing 106. Importantly, the wave generator plug 104 is oval in shape and is disposed within the ball bearing 106 so that the ball bearing 106 can conform to the oval shape. In this configuration, the outer race of the ball bearing 106 can rotate relative to the wave generator plug 104. In the illustrated embodiment, the flex spline 108 is shown as a cup shape, and in particular, the outer periphery of the cup has a set of gear teeth 110. In the figure, the flexspline is mounted on a ball bearing so that the outer peripheral edge of the flexspline can match the above-mentioned elliptical shape. Note that in this embodiment, the flex spline can be rotated relative to the wave generator plug by the ball bearing. The circular spline 112 is ring-shaped and, importantly, the ring inner circumference has a series of gear tooth sets. Typically, there are more gear teeth in the circular spline 114 than the flex spline gear teeth 110. In many embodiments, the circular spline 112 has two more gear teeth than the flexspline 108. In general, the flexspline 108 fits within the circular spline 112 such that the flexspline gear teeth 110 mesh with the gear teeth of the circular spline 114. In particular, since the gear teeth 110 of the flexspline conform to an elliptical shape, only the gear teeth close to the major axis of the elliptical shape normally engage with the gear teeth of the circular spline 114. Conversely, flexspline gear teeth 110 close to the elliptical minor axis disengage from the circular spline 114 gear teeth. In many embodiments, 30% of flexspline gear teeth 110 engage the gear teeth of circular spline 114. With this configuration, the wave generator plug 104 can rotate in a first direction around the elliptical central axis, thereby causing the flexspline 108 to rotate around the elliptical central axis in a second opposite direction at different rotational speeds. It can be rotated (generally more slowly). This can be accomplished by forming the flexspline 108 from a flexible material that can accommodate the deflection resulting from the rotation of the wave generator plug 114.

  2A-2D illustrate the normal operation of a wave gear device according to an embodiment of the present invention that can be made from a BMG-based material. In particular, FIG. 2A shows a wave gear device in which the wave generator plug 204 is in a first orientation with the major axis of the ellipse being perpendicular to the drawing. This start position is designated as “0 °”. Arrow 216 designates one of the gear teeth of flexspline 208 considered for purposes of illustration in FIGS. FIG. 2B shows that the wave generator plug 204 has been rotated 90 ° clockwise. The rotation of wave generator plug 204 causes flex spline 208 to deflect in a particular manner so that the gear tooth corresponding to arrow 216 is disengaged from the gear tooth of circular spline 214. In particular, the gear teeth corresponding to arrow 216 are rotating slightly counterclockwise in relation to the 90 ° clockwise rotation of wave generator plug 204. In FIG. 2C, the wave generator plug 204 is further rotated 90 ° clockwise and rotated 180 ° clockwise relative to the initial start position. In the figure, the gear teeth designated by arrows 216 are re-engaged with the gear teeth of the circular spline 214 in a slightly counterclockwise position relative to the initial starting position. FIG. 4D shows that the wave generator plug 204 is fully rotated 360 ° clockwise relative to the initial starting position. As a result, the gear tooth indicated by 216 is rotating further counterclockwise than the position shown in FIG. 2C. Overall, in FIGS. 2A-2D, it can be seen that a complete 360 ° rotation in one direction of the wave generator plug 204 results in a slight reverse rotation of the flexspline 208. In this way, the wave gear device can achieve a relatively high reduction ratio within a small installation area. In general, the input torque is applied to the wave generator plug 204 and the flex spline 208 generates a corresponding output torque.

  Of course, although examples of wave gear device designs have been shown and described, it should be understood that any suitable wave gear device design and wave gear component can be made from BMG-based materials in accordance with embodiments of the present invention. For example, the flexspline can take any suitable shape and need not be “cup-shaped”. Similarly, any type of bearing can be implemented rather than a ball bearing. For example, a needle roller bearing can be mounted. Specifically, this application is not intended to be limited to any particular wave gear device design or wave gear device component design. In the following, it will be described in detail how a BMG-based material can be embodied in a wave gear device component to improve the performance of the wave gear device according to the present invention.

BMG-Based Wave Gear Device and Wave Gear Device Component In many embodiments of the present invention, BMG-based material is incorporated into a wave gear device and / or a wave gear device component. In many embodiments, BMG-based materials can be developed to have the desired material properties that are very suitable for the fabrication of wave gear device components. For example, from the principle of operation of the wave gear device described above, it goes without saying that the ball bearing and the flex spline are periodically displaced by the rotation of the wave generator plug. As a result, it is desirable to make these components from materials having high fatigue strength. For example, FIG. 3 illustrates how flex spline fatigue strength can be a major determinant of wave gear device life. In particular, when a flexspline fatigues and causes permanent deformation (as opposed to other failure modes), the flexspline in a wave gear device typically fails.

In general, the fatigue limit of a material is defined by the number of times that a certain level of stress can be applied to the material before it is permanently deformed. Assuming that the same periodic cycle load is applied many times, the lower the load, the longer the material lasts before it is deformed. The cycle load that a material can withstand 10 ⁷ cycles is commonly referred to as the fatigue limit of the material. If a material is subjected to a cyclic load at its yield strength, it is expected to break in the cycle. Thus, fatigue limits are generally reported as a percentage of yield strength (normalizing their performance). As shown, 300M steel has a fatigue limit that is 20% of its yield strength. Assuming a constant geometry (surface shape) part is fatigued, such as in a flexspline, incorporating more flexible material results in less stress per cycle, resulting in fatigue life Can be made considerably longer.

  Accordingly, the BMG-based material can preferably be incorporated into the flex spline of the wave gear device to provide improved fatigue performance. For example, BMG-based materials can have an elastic limit of as much as 2% and can be about three times less stiff than steel-based materials. In general, this means that flexsplines made from BMG-based materials can be subjected to lower stresses per deformation unit compared to steel-based flexsplines having the same geometry. Accordingly, BMG-based materials can have even more favorable fatigue properties, for example, materials that are subjected to relatively low stress tend to withstand more load cycles. Furthermore, note that different stiffness values affect the geometry of the fabricated component. Thus, the BMG-based material can have a relatively low stiffness value (e.g., compared to steel), and the wave gear device component can have a more favorable geometry. For example, a relatively low stiffness allows a thicker flexspline to be implemented, which is advantageous. Indeed, the material property profile of BMG-based materials generally allows the development of more favorable geometries, i.e., in addition to stiffness, other material properties of BMG-based materials can also contribute to advantageous geometry development. .

  Furthermore, as can be appreciated from the prior art, BMG-based materials can have higher hardness values, and accordingly demonstrate improved wear performance compared to existing engineering materials. A material with a high hardness value is particularly advantageous in wave gearing, since the components of the wave gearing are in continuous contact with one another and are subject to sliding friction, for example. In general, when the gear teeth are subjected to a constant load and associated friction, the resulting associated elastic deformation and wear can prematurely cause “ratcheting”. BMG-based materials can have high hardness values, good wear resistance (including good wear resistance), and high elasticity, which can have even when subjected to high loads, It can be made more suitable to be embodied in. For example, when a BMG material is embodied in the gear teeth of a wave gear device, ratcheting can be suppressed. Furthermore, the BMG-based material can be formed to have a high hardness value in a wide temperature range. For example, a BMG-based material can have a hardness value that does not change more than 20% as a function of temperature within a temperature range of 100K to 300K. Indeed, BMG-based materials can have a strength that does not change more than 20% as a function of temperature within the temperature range of 100K to 300K. In general, the implementation of BMG-based materials in a wave gear device can be preferred at various levels. Table 1 shows how the material properties of certain BMG-based materials have improved material properties in many ways compared to existing engineering materials.

  Importantly, the material properties of BMG-based materials are a function of the relative proportions of the constituent components and are also a function of the crystal structure. As a result, the material properties of the BMG-based material can be adjusted by changing the composition and by changing the ratio of the crystal structure to the amorphous structure. For example, in many embodiments, it is desirable to implement a BMG-based material having a specific material profile within a specific wave gear device component. In these embodiments, suitable BMG-based materials can be developed and / or selected from among the developed wave gear device components. Tables 2, 3 and 4 show how the material properties of BMG-based materials change based on composition and crystal structure.

  FIG. 5 shows how the hardness of the titanium BMG-based material varies in relation to the alloy composition. In general, titanium BMG-based alloys tend to have many properties, which make them particularly well suited for making wave gear devices and wave gear device components.

  Tables 5 and 6 below show how the fatigue properties of BMG-based materials change as a function of composition.

  Although the data in Tables 5 and 6 are shown, one of the inventors herein performed an independent fatigue test, which is somewhat inconsistent with the data values shown. 4A and 4B show the results of the tests performed.

  In particular, FIG. 4A shows the fatigue resistance of monolithic Vitreloy 1, composite LM2, composite DH3, 300-M steel, 2090-T81-aluminum, and glass ribbon. These results demonstrate that the composite material DH3 exhibits high resistance to fatigue failure. For example, the composite DH3 shows that it can withstand about 20,000,000 cycles with a stress amplitude / tensile strength ratio of about 0.25. Note that monolithic Vitreloy 1 exhibits a relatively low resistance to fatigue failure, which appears to be inconsistent with the results shown in Tables 5 and 6. This difference may be due in part to the rigor of obtaining data. In particular, the inventors of the present invention understand that fatigue resistance is a critical material property that determines whether it is appropriate for various applications, so the inventors have obtained fatigue resistance data obtained under the most severe test conditions. Won. FIG. 4A is reproduced from Non-Patent Document 13 (Launey, PNAS, Vol. 106, No. 13, 4986-4991), the disclosure of which is hereby incorporated by reference. Are listed as co-authors).

  Similarly, FIG. 4B shows DV1 (“silver boat”, manufactured using semi-solid processing), DV1 (“Indus”, manufactured using industry standard procedures), composite DH3, composite. The fatigue resistance of LM2, monolithic Vitreloy 1, 300-M steel, 2090-T81 aluminum, and Ti-6Al-4V bimodal is shown. These results indicate that composite DV1 (silver boat) even exhibits greater resistance to fatigue failure than composite DH3. It should be noted that the results of testing composite material DV1 vary largely based on how composite material DV1 was manufactured. When manufactured using the “silver boat” technology (“silver boat” refers to semi-solid manufacturing technology and is non-patent document 14 (Hofmann, JOM, Vol. 61, No. 12, 11-17). And this disclosure is incorporated herein by reference), and exhibited significantly better resistance to fatigue than when manufactured using industry standard techniques. The inventor of the present invention attributed this difference to the fact that the industry standard manufacturing process does not impose the type of rigor required to produce a sufficiently pure material, and this is due to fatigue failure. This is a factor that can be made by the industry that does not recognize how important the material composition is in determining the material properties, including resistance to. FIG. 4B was created jointly by Launey with the results in FIG. 4A, but FIG. 4B has not been published in the above cited references.

  In general, FIGS. 4A and 4B show that BMG-based materials can be developed to have better fatigue properties than steel and other existing engineering materials. Importantly, FIGS. 4A and 4B show relative stress amplitude ratios and, as can be derived from Table 1, BMG-based materials are formed to have a better maximum tensile strength than many steels. be able to. Thus, BMG-based materials can be formed to withstand more load cycles at higher stress levels than some steels. Furthermore, BMG-based materials can be formed to have low stiffness, so that they can be formed to receive less stress per unit excursion, resulting in even better fatigue performance. .

  From the above description, it is clear that BMG-based materials can have advantageous material properties that can be very well suited for implementation in wave gearing components. Any of the listed BMG-based materials can be embodied in a wave gear device component according to embodiments of the present invention. More generally, the BMG-based material is adjusted (eg, through alloying and / or heat treatment) to obtain a material having a desired material profile that is embodied in a wave gear device, according to embodiments of the invention. be able to. In general, a desired material property profile can be determined for each wave gear component, and BMG-based materials that match the material property profile can be developed and implemented.

  For example, in many embodiments where a low stiffness material is desired, the relative proportion of B, Si, Al, Cr, Co, and / or Fe within the BMG-based composition is reduced. Similarly, in many embodiments where a low stiffness material is desired, the volume fraction of soft, ductile dendrites is high; or alternatively, beta stable elements such as V, Nb, Ta, Mo, And / or the amount of Sn increases. In general, in BMGMCs, the material stiffness varies according to the mixing rules, for example, if there are relatively many dendrites, the stiffness decreases, and if there are relatively few dendrites, the stiffness increases. It should be noted that, generally speaking, when changing the stiffness of a BMG-based material, the stiffness can be greatly changed without affecting other properties, such as the elastic strain limit or workability of the BMG-based material. The ability to adjust stiffness without affecting other material properties or workability is a significant advantage in the design of wave gearing and wave gearing components.

  Furthermore, since the rigidity of the BMG material can be adjusted, the resistance to fatigue failure can also be adjusted according to the embodiment of the present invention. The alloy elements used to improve resistance to fatigue failure are largely determined experimentally. However, it has been observed that the same processing techniques used to increase fracture toughness also tend to favorably affect resistance to fatigue failure.

In any case, as is apparent from the above description, any of the BMG-based materials listed above and described can be incorporated into the wave gear device and the wave gear device component in accordance with embodiments of the present invention. . More generally, any BMG-based material can be embodied in the wave gear device and wave gear device components in accordance with embodiments of the present invention. For example, in many embodiments, the embodied BMG-based material is based on Fe, Zr, Ti, Ni, Hf, or Cu (i.e., each of these elements has a greater amount than any other element). Present in the material). In some embodiments, the BMG-based material embodied in the wave gear device component is a Cu-Zr-Al-X composition, where X is, for example, Y, Be, Ag, Co, Fe, Cr, One or more elements of C, Si, B, Mo, Ta, Ti, V, Nb, Ni, P, Zn and Pd. In some embodiments, the BMG-based material embodied in the wave gear device component is a Ni-Zr-Ti-X composition, where X is, for example, Co, Al, Cu, B, P, Si, One or more elements of Be and Fe. In many embodiments, the BMG-based material embodied in the wave gear component is a Zr—Ti—Be—X composition, where X is, for example, Y, Be, Ag, Co, Fe, Cr, C, One or more elements of Si, B, Mo, Ta, Ti, V, Nb, Ni, P, Zn and Pd. In some embodiments, the wave gear device component comprises a BMG-based material that is Ni ₄₀ Zr _28.5 Ti _16.5 Al ₁₀ Cu ₅ (atomic proportion). In some embodiments, the wave gear device component comprises a BMG-based material that is (Cu ₅₀ Zr ₅₀ ) _x Al _1-12 Be _1-20 Co _0.5-5 . In many embodiments, a desired material profile is determined for a wave gear device component, and a BMG-based material having the desired characteristics is used to construct the wave gear device component. Since BMG-based materials can have many advantageous properties, implementation within a wave gear device component can result in a more robust wave gear device. This design method and production of the BMG wave gear device will be described in detail below.

Fabrication of BMG-based wave gear devices and wave gear device components In many embodiments of the present invention, wave gear device components are fabricated from BMG-based materials using casting or thermoplastic forming techniques. Casting techniques or thermoplastic forming techniques can greatly improve efficiency, which creates wave gearing and wave gearing components. For example, steel wave gear components are typically machined, and the cost of machining is considerable due to the complexity of the component components. Conversely, the use of casting or thermoplastic forming techniques in the development of wave gear component can avoid overly costly machining processes.

  A method of making a wave gear device component incorporating casting or thermoplastic forming techniques is shown in FIG. This process has a step 610 of determining the desired material profile of the component to be fabricated. For example, when creating a flexspline, a component material has a specific stiffness, a specific resistance to fatigue failure, a specific density, a specific resistance to brittle fracture, a specific resistance to corrosion, a specific resistance to wear It is desirable to have a certain level of glass forming ability. In many embodiments, material cost is also a major consideration (eg, certain BMG-based materials can be higher or cheaper than other BMG-based materials). In general, any parameter can be a factor in the step 610 of determining the material profile for the component to be fabricated.

  It should be noted that any component in a wave gear device can be made according to embodiments of the present invention. As pointed out above, flexsplines and ball bearings are subject to periodic deformations, so it is particularly advantageous to form them from materials that are highly resistant to fatigue failure. In addition, flexsplines and ball bearings are also beneficial by forming from materials that have extremely high resistance to wear, which means that the components are in constant contact and relative during normal operation of the wave gearing. (The flexspline gear teeth are worn, and the ball bearing balls and the inner and outer races are subject to wear). In some embodiments, ball bearing balls are made from BMG-based materials, and in this way, ball bearing balls can benefit from the improved wear resistance that BMG-based materials can provide.

  However, it is clear that any component of a wave gear device can be made from a BMG-based material according to embodiments of the present invention. In some embodiments, the circular spline gear teeth are made from a BMG-based material. In this way, circular spline gear teeth can benefit from the improved wear performance characteristics that BMG-based materials can exhibit. In some embodiments, circular spline gear teeth made from BMG-based material are then press fit into different, more rigid materials, such as barium and titanium, but form a circular spline, Keep in mind that it is beneficial for a relatively stiff circular spline in supporting the movement of the flexspline and wave generator. In this way, the BMG-based material is embodied in a circular spline gear tooth that can exhibit improved wear performance, and the stiffer material forms the remainder of the circular spline that can exhibit improved structural support. can do.

  In many embodiments, the majority of the components of the wave gear device are made from the same BMG-based material, and in this way, each wave gear device can have a more uniform coefficient of thermal expansion. In any case, any component of the wave gear device can be made from a BMG-based material according to embodiments of the present invention.

  Referring back to FIG. 6, a BMG material that satisfies the determined material profile is selected (step 620). Any suitable BMG-based material can be selected, and these BMG-based materials include all of those listed in Tables 1-5 and shown in FIGS. In many embodiments, a BMG-based material is specifically developed and selected at step 620 to satisfy the material profile determined at step 610. For example, in many embodiments, certain BMG-based materials are developed by alloying in any suitable manner (eg, as detailed above) to fine tune material properties. In many embodiments, BMG-based materials are developed by changing the ratio of crystal structure to amorphous structure (eg, as detailed above) to fine tune material properties. Of course, any suitable method of developing a BMG-based material that satisfies the material properties determined in step 610 can be implemented in accordance with embodiments of the present invention.

  The BMG-based material selected in step 620 is, for example, thermoplastically formed into a desired shape (eg, the shape of the component to be made) or formed using a casting technique. While gear-type component fabrication by casting or thermoplastic technology from BMG-based materials is not widely prevalent, the inventors of the present invention have demonstrated the feasibility of such technology for this purpose. For example, FIGS. 7A-7D show a 1 inch radius gear made from a BMG-based material using a single casting step. In particular, FIG. 7A shows a steel mold used for gear formation. FIG. 7B shows the removal of BMGMC material from the steel mold. Figures 7C and 7D show SEM images that demonstrate the fidelity of the fabricated components. In particular, gear teeth were also implemented using this fabrication method. In this way, gear teeth can be complicated and expensive machining can be avoided (in contrast, steel based wave gear components generally rely on machining in component formation). Thus, in accordance with this teaching, in many embodiments, the BMG-based material is thermoplastically formed or cast into the shape of a component of a wave gear device. In many embodiments, the BMG-based material is thermoplastically formed or cast into the shape of a component that includes the shape of a gear tooth. Furthermore, it should be noted that any suitable thermoplastic forming or casting technique can be implemented in accordance with embodiments of the present invention. For example, the component of the wave gear device can be formed by one of direct casting technology, forging technology, spin forming technology, blow molding technology, centrifugal casting technology, and thermoplastic forming technology using BMG powder. it can. As can be appreciated by those skilled in the art, BMG-based materials must cool quickly enough to maintain at least some amorphous structure. Of course, it should be noted that the wave gearing component can be formed from a BMG-based material in any suitable manner, including machining, in accordance with embodiments of the present invention.

  By way of example, FIGS. 8A-8D illustrate a direct casting technique that can be implemented to form the constituent components of a wave gear device in accordance with an embodiment of the present invention. In particular, FIG. 8A shows the situation of a molten BMG-based material 802 that is heated to a molten state, thereby ready to be inserted into a mold 804. The mold 804 serves to define the shape of the component to be formed. FIG. 8B shows the situation where the molten BMG-based material 802 is pressed into the mold 804. FIG. 8C shows a situation where the mold 804 is released after the BMG-based material is cooled. FIG. 8D shows a situation where any excess flush (excess portion) is removed. Accordingly, wave gear component can be made using direct casting techniques in conjunction with BMG-based materials, in accordance with embodiments of the present invention. It should be noted that crystalline metal casting suitable for implementation in wave gearing components is generally not feasible.

  9A-9C illustrate other forming techniques that can be implemented in accordance with embodiments of the present invention. In particular, FIGS. 9A-9C illustrate thermoplastic forming a BMG-based material in sheet form according to an embodiment of the present invention. In particular, FIG. 9A shows a sheet 902 of BMG-based material that has been heated to perform this thermoplastic formation. In the illustrated embodiment, the BMG-based material sheet 902 is heated by capacitive discharge technology, but it should be understood that any suitable heating method may be implemented in accordance with embodiments of the present invention. FIG. 9B shows a situation where a press is used to push BMG-based material into a mold 904 to form a component to be fabricated. FIG. 9C shows a situation where the mold 904 is released to remove any excess flush. In this way, the desired component is obtained.

  As noted above, heating of the BMG-based material that can be thermoplastic formed can be accomplished in any suitable manner in accordance with embodiments of the present invention. For example, FIGS. 10A-10C show that heating of BMG-based material in sheet form can be achieved by spinning friction. 10A-10C are similar to those seen in FIGS. 9A-9C, except that they are pressed against the BMG material 1002 and frictionally heat the BMG sheet material by rotation of the press 1010. ing. In this way, the BMG material can be heated to such an extent that it can be thermoplastically formed. This technique is called “spin formation”.

  It should be noted that while the above description relates to mechanically matching a BMG-based material to a mold, the BMG-based material may be formed in the mold in any suitable manner in accordance with embodiments of the present invention. it can. In many embodiments, the BMG-based material is matched to the mold using one of forging techniques, vacuum techniques, drawing techniques, and magnetic forming techniques. Of course, the BMG-based material can be matched to the mold in any suitable manner in accordance with embodiments of the present invention.

  11A-11C illustrate the situation of forming a part using a blow molding technique. In particular, FIG. 11A shows a situation where a BMG-based material is placed in a mold. FIG. 11B shows a situation in which the BMG-based material 1102 is exposed to a pressurized gas or liquid, and the BMG-based material matches the shape of the mold 1104. In general, a pressurized inert gas is used. As usual, the BMG-based material is heated as usual so that it can be easily molded and can be affected by pressurized gas or liquid. Again, any suitable heating technique can be implemented according to embodiments of the present invention. FIG. 11C shows a situation where the BMG-based material matches the shape of the mold 1104 due to the force of the pressurized gas or liquid.

  12A and 12B illustrate that centrifugal casting can be performed to form the constituent components of a wave gear device. FIG. 12A shows a situation where molten BMG-based material 1202 is poured into mold 1204 and the mold is rotated to match the BMG-based material to the shape of the mold.

  FIGS. 13A-13C show that a BMG-based material is charged into a mold in the form of a powder and then heated to make the material ready for thermoplastic formation, thereby achieving the desired component according to an embodiment of the present invention. It shows forming to make the shape of. In particular, FIG. 13A shows a situation where a powdered BMG-based material 1302 is deposited in a mold. FIG. 13B shows a situation where the BMG-based material 1302 is heated and pressed to match the shape of the mold 1304. FIG. 13C shows a situation where the BMG-based material has solidified, thereby forming a desired component.

  In general, it will be apparent that any technique suitable for thermoplastic forming or casting a BMG-based material can be implemented in accordance with embodiments of the present invention. The above examples are meant to be illustrative and are not comprehensive. More generally, any technique suitable for forming a wave gear component comprised of a BMG-based material can be implemented in accordance with embodiments of the present invention.

  Returning to FIG. 6, the process 600 further includes a step 640 of performing an optional post-forming operation to finish the fabricated component, if desired. For example, in some embodiments, the overall shape of the flexspline is thermoplastic formed or cast and then the gear teeth are machined against the flexspline. In some embodiments, a twin roll forming technique is applied to provide the gear teeth on the flexspline or circular spline. FIG. 14 shows a twin roll forming arrangement that can be used to implement gear teeth in a flexspline. In particular, the arrangement 1400 has a first roller that supports the movement of the flexspline 1402 by this arrangement and a second roller 1412 that acts to define gear teeth in the flexspline. The flexspline 1402 is heated to make it easier to mold and ready to be defined by the second roller. Of course, the roll formed part can be finished using any suitable technique according to embodiments of the present invention. For example, the gear teeth can be implemented using conventional machining techniques. In addition, the roll-formed part can be finished in any suitable manner (not only to define gear teeth) according to embodiments of the present invention.

  15A-15F show the creation of a flexspline according to the process outlined in FIG. FIG. 15A shows a multi-piece mold used to cast the overall shape of the flexspline, FIG. 15B shows an assembled multi-piece mold used to cast the overall shape of the flexspline, FIG. 15C shows flexspline casting using BMG-based material, FIG. 15D shows mold dismantling, FIG. 15E shows flexspline removed from the mold, and FIG. 15F shows flexspline after casting from BMG-based material. It can be shown that gear teeth can be machined. It should be noted that although the drawing shows machining the gear teeth into a flex spline, the flex spline can be cast to have the desired gear teeth. In this way, costly machining can be avoided.

Note that the forming technique is extremely sensitive with respect to process control. In general, it is beneficial to precisely control fluid flow, ventilation, temperature, and cooling when forming parts. For example, FIG. 16 shows several attempts at flexspline formation using casting techniques, showing that many attempts are clearly incomplete. In particular, seven samples in the image were made using a BMG-based material of TiZrCuBe having a density of 5.3 g / cm ³ . The rightmost sample in the image was made from Vitreloy1.

  FIG. 17 illustrates the creation of parts of various scales using the process described above. As an example, FIG. 17 shows a larger flexspline made according to the process described above, as well as a smaller flexspline made according to the process described above. In this way, the process described above is versatile.

  It should be understood that while FIGS. 15-17 relate to the creation of a flexspline, any wave gear device component can be made from a BMG-based material in accordance with embodiments of the present invention. For example, FIGS. 18A-18B show a circular spline made from a BMG-based material. In particular, FIG. 18A shows a titanium BMG-based material from which a 1.5 inch circular spline was made, and FIG. 18B shows the produced circular spline for the produced flexspline. Although circular splines are not shown as having gear teeth, the gear teeth can subsequently be machined into circular splines.

  The fabrication techniques described above can be used to efficiently fabricate wave gear devices and wave gear device components. For example, as is pointed out implicitly in the above description, the costs associated with machining components can be avoided using these techniques. Therefore, the cost of producing a wave gear device component is primarily a function of raw material cost, which can be said regardless of the size of the component. Conversely, when forming a steel-based wave gear component, the cost of manufacturing the part increases with a size reduction that exceeds some critical value. This is because it is difficult to machine smaller size parts.

  As an example, FIG. 19 shows the relationship for flexsplines that the raw material cost of amorphous metal is higher than steel. For example, the stiffness of the steel may require the flexspline to have a diameter that is less than some specific amount, for example 20.8 mm (2 inches), and a wall thickness that is less than some amount, for example 1 mm. To illustrate the situation, FIG. 20 shows a steel-based flexspline having a diameter of 50.8 mm (2 inches) and a wall thickness of 0.8 mm. Significantly, when the flexspline is made smaller, eg, less than 1 inch in diameter, the steel wall becomes too thin to facilitate machining. As a result, even when the cost of the amorphous metal raw material is higher than that of steel, the flexspline can be made cheaper when manufactured from amorphous metal. In short, laborious machining can be eliminated by casting parts from BMG-based materials, and the cost of flexsplines can thereby be reduced.

  As can be inferred from the above description, the above concept can be embodied in various configurations according to embodiments of the present invention. For example, in some embodiments, the wave gear device component is cast from a polymer material and then coated with a bulk metallic glass-based material. In this way, the wear resistance characteristics of the bulk metallic glass-based material can be utilized. Thus, although the invention has been described in certain embodiments, many additional changes and modifications will be apparent to those skilled in the art. Accordingly, it should be understood that the invention can be practiced otherwise than as specifically described herein. Accordingly, the embodiments of the present invention should be considered in all respects as illustrative and not restrictive.

U.S. Patent No. 13/928109 US Patent No. 13/949322

G. Kumar et al., Adv. Mater. 2011, 23, 461-476 M. Ashby et al., Scripta Materialia 54 (2006) 321-326 Conner, Journal of Applied Physics, Volume 94, Number 2, July 15, 2003, pgs.904-911 Wu, Trans. Nonferrous Met. Soc. China 22 (2012), 585-589; Wu, Intermetallics 25 (2012) 115-125) Kong, Tribal Lett (2009) 35: 151-158; Zenebe, Tribol Lett (2012) 47: 131-138 Chen, J. Mater. Res., Vol. 26, No. 20, Oct 28, 2011; Liu, Tribol Lett (2012) 46: 131-138 I.L.Singer, Wear, Volume 195, Issues 1-2, July 1996, Pages 7-20 Chen, J. Mater. Res., Vol. 26, No. 20, Oct 28, 2011 Huang, Intermetallics 19 (2011) 1385-1389 Liu, Tribol Lett (2009) 33: 205-210 Zhang, Materials Science and Engineering A, 475 (2008) 124-127 Ishida, Materials Science and Engineering A, 449-451 (2007) 149-154 Launey, PNAS, Vol. 106, No. 13, 4986-4991 Hofmann, JOM, Vol. 61, No. 12, 11-17

Claims (20)

A wave generator;
A flexspline having a first set of gear teeth;
A circular spline having a second set of gear teeth;
With
A wave gear device in which at least one of the wave generating device, the flex spline, and the circular spline includes a bulk metallic glass-based material.   The wave gear device according to claim 1, wherein the wave generator includes a wave generator plug and a bearing.   The wave gear device according to claim 2, wherein the bearing is a ball bearing.   2. The wave gear device according to claim 1, wherein each of the wave generating device, the flex spline, and the circular spline includes a bulk metallic glass-based material.   The wave gear device according to claim 1, wherein at least one of the first set of gear teeth and the second set of gear teeth includes a bulk metallic glass-based material.   2. The wave gear device according to claim 1, wherein each of the first set of gear teeth and the second set of gear teeth includes a bulk metallic glass-based material.   The wave gear device according to claim 6, wherein the wave generating device includes a ball bearing including a bulk metallic glass-based material.   2. The wave gear device according to claim 1, wherein the element of the bulk metallic glass-based material existing in a maximum amount is one of Fe, Zr, Ti, Ni, Hf, and Cu. The wave gear device according to claim 1, wherein the bulk metallic glass-based material is Ni ₄₀ Zr _28.5 Ti _16.5 Al ₁₀ Cu ₅ . A wave generator plug having an elliptical cross section;
A bearing having an inner race, an outer race and a plurality of rolling members;
With
The wave generator plug is disposed within the bearing so that the bearing can conform to the elliptical shape of the wave generator plug;
At least one of the wave generator plug and the bearing includes a bulk metallic glass-based material.   11. The wave generator according to claim 10, wherein the bearing is a ball bearing.   A flexspline comprising a flexible body defining a circular shape, wherein the circular perimeter defines a set of gear teeth, and the flexible body comprises a bulk metallic glass-based material.   The flexspline of claim 12, wherein the set of gear teeth includes a bulk metallic glass-based material.   A circular spline comprising a ring-shaped body, the inner periphery of the ring-shaped body defining a set of gear teeth, wherein the ring-shaped body comprises a bulk metallic glass-based material.   The circular spline of claim 14, wherein the set of gear teeth includes a bulk metallic glass-based material. A method of making a wave gear device component comprising:
Forming a BMG-based material using a mold associated with one of a thermoplastic forming technique and a casting technique;
The BMG-based material includes a wave generator plug, an inner race, an outer race, a rolling element, a flex spline, a flex spline without a set of gear teeth, a circular spline, and a circular spline without a set of gear teeth. , Molded as one of a set of gear teeth to be incorporated into a flexspline and a set of gear teeth to be incorporated into a circular spline.   The method of claim 16, further comprising machining the BMG-based material after molding by either thermoplastic forming or casting techniques.   18. The method of claim 17, wherein the BMG-based material is molded as one of a flexspline without a set of gear teeth and a circular spline without a set of gear teeth, and gear teeth are said A method of machining a BMG-based material.   The method of claim 18, wherein the BMG-based material is molded as one of a flexspline without a set of gear teeth and a circular spline without a set of gear teeth, wherein the gear teeth are A method embodied for BMG-based materials using a twin roll forming technique.   17. The method of claim 16, wherein the BMG-based material is molded using one of direct casting technology, blow molding technology, and centrifugal casting technology.